Vehicle steering device

Abstract

A vehicle steering device includes a steering wheel operated by a driver to steer a vehicle; a steering reaction force motor that applies a reaction force to the steering wheel; a turning device that turns turning wheels of the vehicle by a turning motor; a clutch mechanism that mechanically connects and disconnects the steering wheel with and from the turning device; a control device that provides control so that a turning angle is based on a steering angle of the steering wheel; and a temperature sensor that measures a temperature. The vehicle steering device mechanically couples the steering wheel and the turning device and activates the steering wheel and the turning device if the temperature is a predetermined value or lower.

We claim: 
     
       1. A vehicle steering device comprising:
 a steering member operated by a driver to steer a vehicle; 
 a reaction force motor that applies a reaction force to the steering member; 
 a turning mechanism that turns turning wheels of the vehicle by a turning motor; 
 a clutch that mechanically connects and disconnects the steering member with and from the turning mechanism; 
 a control unit that provides control so that a turning angle is based on a steering angle of the steering member; and 
 a control device that acquires a temperature by measuring or estimating the temperature, 
 wherein, the control device determines, before activating the vehicle steering device, whether the temperature is a predetermined value or lower, and when the temperature is the predetermined value or lower, the steering member and the turning mechanism are mechanically coupled by the clutch and the vehicle steering device is activated with a manual steering mode or an electronic power steering mode, and when the temperature is higher than the predetermined value, the steering member and the turning mechanism are mechanically disconnected by the clutch and the vehicle steering device is activated with a steer by wire mode, 
 wherein the temperature is a temperature around the turning mechanism, a temperature of a turning gear box of the turning mechanism, or an ambient temperature surrounding the vehicle. 
 
     
     
       2. The vehicle steering device according to  claim 1 , wherein the control device includes a temperature measurement unit connected with the control unit. 
     
     
       3. The vehicle steering device according to  claim 2 , wherein the temperature is the temperature of the turning gear box, and the temperature measurement device measures the temperature of the turning gear box. 
     
     
       4. The vehicle steering device according to  claim 1 , wherein the control device acquires the temperature by estimating the temperature based on any of temperature information of an external thermometer, air-conditioner operation information, seat-heater temperature rise characteristic information, tire pressure information, information of a tire pressure monitoring system, information of a navigation device, and information received through the Internet. 
     
     
       5. The vehicle steering device according to  claim 4 , wherein the temperature is the ambient temperature surrounding the vehicle. 
     
     
       6. The vehicle steering device according to  claim 1 , wherein, when a state, in which the temperature acquired by the control device is the predetermined value or lower, continues for a predetermined time or longer, the steering member and the turning mechanism are mechanically coupled and the vehicle steering device is activated with the manual steering mode or the electronic power steering mode. 
     
     
       7. The vehicle steering device according to  claim 1 , wherein, after the steering member and the turning mechanism are mechanically coupled and the vehicle steering device is activated, when the temperature acquired by the control device exceeds the predetermined value, an operation mode is shifted to the steer by wire mode in which the steering member and the turning mechanism are not mechanically coupled. 
     
     
       8. The vehicle steering device according to  claim 1 , further comprising:
 a turning motor current detection device that detects a current value of the turning motor, 
 wherein, after the steering member and the turning mechanism are mechanically coupled and the vehicle steering device is activated, when a current integrated value of the turning motor becomes a predetermined value or larger, an operation mode is shifted to the steer by wire mode in which the steering member and the turning mechanism are not mechanically coupled. 
 
     
     
       9. The vehicle steering device according to  claim 8 , wherein the predetermined value is changed in accordance with the acquired temperature. 
     
     
       10. The vehicle steering device according to  claim 1 , wherein at least two motors are driven in the electronic power steering mode. 
     
     
       11. The vehicle steering device according to  claim 10 , further comprising:
 a reaction force motor current detection device that detects a current value of the reaction force motor, 
 wherein, after the steering member and the turning mechanism are mechanically coupled and the vehicle steering device is activated, the reaction force motor is driven in the electronic power steering mode, and when a current integrated value of the reaction force motor is increased to a predetermined value, an operation mode is shifted to the steer by wire mode in which the steering member and the turning mechanism are not mechanically coupled. 
 
     
     
       12. The vehicle steering device according to  claim 11 , wherein the predetermined value is changed in accordance with the acquired temperature. 
     
     
       13. The vehicle steering device according to  claim 10 , wherein the at least two motors include the reaction force motor and the turning motor, and the at least two motors provide assist force for steering the vehicle. 
     
     
       14. A vehicle steering device comprising:
 a steering member to steer a vehicle; 
 a reaction force motor that applies a reaction force to the steering member; 
 a turning mechanism that turns turning wheels of the vehicle by a turning motor; 
 a clutch that mechanically connects and disconnects the steering member with and from the turning mechanism; 
 a controller that controls the turning mechanism such that a turning angle of the turning wheels corresponds to a steering angle of the steering member; and 
 a control device that acquires a temperature by measuring or estimating the temperature, 
 wherein, the control device determines, before activating the vehicle steering device, whether the temperature is a predetermined value or lower, and when the temperature is the predetermined value or lower, the controller mechanically connects the steering member to the turning mechanism by the clutch and activates the vehicle steering device with a manual steering mode or an electronic power steering mode, and when the temperature is higher than the predetermined value, the controller mechanically disconnects the steering member and the turning mechanism by the clutch and activates the vehicle steering device with a steer by wire mode, and 
 wherein the temperature is a temperature around the turning mechanism, a temperature of a turning gear box of the turning mechanism, or an ambient temperature surrounding the vehicle. 
 
     
     
       15. The vehicle steering device according to  claim 14 , wherein the temperature is the temperature around the turning mechanism. 
     
     
       16. A method for controlling a vehicle steering device, the method comprising:
 obtaining, by using a controller, a temperature as to a vehicle; 
 deciding, by using the controller, whether the temperature is a predetermined value or lower before activating the vehicle steering device; and 
 when the temperature is the predetermined value or lower, mechanically connecting, by using the controller, a steering member to a turning mechanism by a clutch and activating the vehicle steering device with a manual steering mode or an electronic power steering mode, and when the temperature is higher than the predetermined value, mechanically disconnecting the steering member and the turning mechanism by the clutch and activating the vehicle steering device with a steer by wire mode, 
 wherein the steering member steers the vehicle, the turning mechanism turns turning wheels of the vehicle by a turning motor, and 
 wherein the temperature is a temperature around the turning mechanism, a temperature of a turning gear box of the turning mechanism, or an ambient temperature surrounding the vehicle.